1. Field of the Invention
The invention relates to a wireless receiving apparatus including a connector with a plurality of terminals and an electronic appliance that is connected to a wireless receiving apparatus using a connector with a plurality of terminals.
2. Description of the Related Art
In recent years, in the field of television broadcasting, it has become common to record audio transferred using wireless microphones. FIGS. 1A and 1B show an example of the appearance of a wireless microphone. Of such drawings, FIG. 1A shows a wireless microphone transmitter (hereinafter simply called “transmitter”) as an apparatus for transmitting audio. A transmitter 21 transmits radio waves modulated by an audio signal from a microphone.
FIG. 1B shows a wireless microphone receiver (hereinafter simply called “receiver”) as an apparatus for receiving audio. A receiver 22 receives the radio waves transmitted from the transmitter 21 and demodulates the audio signal. A connector 22a that includes a plurality of terminals for outputting an audio signal and inputting an external power supply is provided on a lower surface of the cover of the receiver 22. A display unit (such as a liquid crystal display) 22b for displaying a variety of information is provided on the surface of the cover of the receiver 22 and although not shown in the drawings, an operation unit for carrying out various setting operations is also provided.
FIG. 2A is a diagram showing one example of an audio recording system that uses a wireless microphone. The receiver 22 is attached to a slot 31a provided on a camcorder 31 (i.e., a video camera integrated with a recorder such as a VTR or optical disk apparatus). A connector of the same standard as the connector 22a of the receiver 22 is provided inside the slot 31a (one of such connectors being a male connector and the other a female connector).
The camcorder 31 supplies power to the receiver 22 while receiving audio transmitted from one transmitter 21 using the receiver 22. Such audio is inputted from the connector 22a (see FIG. 1B) of the receiver 22 into the camcorder 31 and is recorded in the camcorder 31 together with images picked up by the camcorder 31.
Until recently, the receiver of a wireless microphone has been only equipped with a function for receiving one channel of audio from a single transmitter. Corresponding to this fact, an existing video camera is only provided with sufficient signal lines (such as communication lines), circuits (such as audio processing circuits), and a power supply capacity for the case where a single-channel receiver is attached to the slot.
However, in recent years, increasing use of multiple audio channels has been made during the production of programs and the like, resulting in demand for individual receivers that can receive a plurality of audio channels. In response to such demand, receivers with a function for receiving a plurality of channels of audio and outputting such audio from a connector are being introduced.
Video cameras that are compatible with multi-channel receivers are also being introduced. Such video cameras have an increased power supply capacity and/or a larger number of signal lines and circuits for inputting audio signals on a plurality of channels when one of the multi-channel receivers described above is attached.
FIG. 2B is a diagram showing the same type of audio recording system as that shown in FIG. 2A. In this system, a multi-channel receiver is shown as a receiver 23, and a video camera that is compatible with the multi-channel receiver is shown as a video camera 32. The receiver 23 is attached to a slot 32a provided on the video camera 32. A connector of the same standard as the connector of the receiver 23 (i.e., a connector that corresponds to the connector 22a in FIG. 1B) is provided inside the slot 32a. 
While power is being supplied from the video camera 32 to the receiver 23, audio transmitted from two transmitters 21 is received by the receiver 23, the audio on two channels is inputted from the connector of the receiver 23 into the video camera 32 and the audio on two channels is recorded by the video camera 32 together with images picked up by the video camera 32.
In this way, it is becoming common for the broadcasting equipment at a television channel to include both multi-channel receivers and older single-channel receivers and both multi-channel-receiver-compatible camcorders and older single-channel-receiver-compatible camcorders.
However, when a multi-channel receiver is attached to a slot of an older single-channel-receiver-compatible camcorder, since the video camera will only have a small power supply capacity designed for a single-channel receiver, not only will the multi-channel receiver be unable to operate but the circuits inside the video camera will also become overloaded.
Also, when an older single-channel receiver is attached to a slot of a multi-channel-receiver-compatible camcorder, the signal lines and circuits that are only used when a multi-channel receiver is attached will not be connected. Thus, there is the possibility of noise appearing in the audio signal due to the effects of external noise and the like and of the operation of the video camera becoming unstable.
Here, as one technique for eliminating such operational difficulties, it would be possible to make the mechanism for attaching a multi-channel receiver to a multi-channel-receiver-compatible camcorder different to the mechanism for attaching a single-channel receiver to a single-channel-receiver-compatible camcorder to make it mechanically difficult to attach a multi-channel receiver to a single-channel-receiver-compatible camcorder, and mechanically difficult to attach a single-channel receiver to a multi-channel-receiver-compatible camcorder.
However, since a variety of appliances aside from receivers are connected to the video camera in the periphery of the slot for attaching a receiver, if the mechanism for attaching a receiver is changed, it will also become necessary to change the mechanisms for connecting other appliances. Changing the mechanisms for connecting various appliances merely in order to change the mechanism for attaching a receiver is also undesirable from the viewpoints of cost and ease of use of the video camera.
Note that although Japanese Unexamined Patent Application Publications No. 2000-14037 and No. H11-215730 each disclose a technology for identifying whether a battery or power supply adapter has been attached to a video camera, a technology for enabling a video camera and a receiver to identify one another has yet been disclosed.